Photocatalytic oxidation of DBP precursors using UV with suspended and fixed TiO2.

French River water (Nova Scotia, Canada) was separated into six different natural organic matter (NOM) fractions, including hydrophobic acids, bases and neutrals and hydrophilic acids, bases and neutrals. The raw water, as well as each of the NOM fractions were analysed for disinfection by-product (DBP) formation potential before and after advanced oxidation with UV/TiO(2) to determine the efficacy of this treatment for the removal of DBP precursors. The UV/TiO(2) treatment was carried out with a nanostructured thin film (NSTF), coated with TiO(2) which is compared with the use of a TiO(2) suspension. For the raw river water, removals of total trihalomethane formation potential (TTHMFP) and total haloacetic acid formation potential (THAA(9)FP) were found to be approximately 20% and 90%, respectively, with 50 mJ/cm(2) UV exposure and 1mg/L TiO(2). For the fractionated samples, approximately 75% of both trihalomethane (THM) and haloacetic acid (HAA) precursors were found to be associated with the hydrophobic acid fraction. For this individual fraction the same UV/TiO(2) treatments exhibited approximately 20-25% removal of both TTHMFP and THAA(9)FP, suggesting that the fractionation process may have affected the treatability of HAA precursors or may have altered the results of the oxidation processes.

Gas adsorption properties of the ternary ZnO/CuO/CuCl(2) impregnated activated carbon system for multigas respirator applications assessed through combinatorial methods and dynamic adsorption studies.

A ternary library of 64 ZnO/CuO/CuCl(2) impregnated activated carbon samples was synthesized and screened automatically using a combinatorial (combi) method. The ability of the samples to adsorb toxic gases was screened gravimetrically. The stoichiometric ratio of reaction (SRR) between the moles of toxicant and the total moles of impregnant was obtained from the calculated mass increase of the samples after chemisorption, with a high SRR indicating high efficiency of toxicant removal. The combi samples that exhibited good dry SO(2) and NH(3) adsorption were prepared in bulk using the incipient wetness method and were evaluated for multigas respirator function by dynamic adsorption studies of SO(2), NH(3), HCN, and C(6)H(12) gases in either dry or humid conditions at ambient temperature. The bulk samples showed equivalent gas adsorption capacities when exposed to the different challenge gases indicating the value of the combi method for initial screening. Cu(2)Cl(OH)(3) was identified to be a potential multigas adsorbent.

Cross-laboratory experimental study of non-noble-metal electrocatalysts for the oxygen reduction reaction.

Nine non-noble-metal catalysts (NNMCs) from five different laboratories were investigated for the catalysis of O(2) electroreduction in an acidic medium. The catalyst precursors were synthesized by wet impregnation, planetary ball milling, a foaming-agent technique, or a templating method. All catalyst precursors were subjected to one or more heat treatments at 700-1050 degrees C in an inert or reactive atmosphere. These catalysts underwent an identical set of electrochemical characterizations, including rotating-disk-electrode and polymer-electrolyte membrane fuel cell (PEMFC) tests and voltammetry under N(2). Ex situ characterization was comprised of X-ray photoelectron spectroscopy, neutron activation analysis, scanning electron microscopy, and N(2) adsorption and its analysis with an advanced model for carbonaceous powders. In PEMFC, several NNMCs display mass activities of 10-20 A g(-1) at 0.8 V versus a reversible hydrogen electrode, and one shows 80 A g(-1). The latter value corresponds to a volumetric activity of 19 A cm(-3) under reference conditions and represents one-seventh of the target defined by the U.S. Department of Energy for 2010 (130 A cm(-3)). The activity of all NNMCs is mainly governed by the microporous surface area, and active sites seem to be hosted in pore sizes of 5-15 A. The nitrogen and metal (iron or cobalt) seem to be present in sufficient amounts in the NNMCs and do not limit activity. The paper discusses probable directions for synthesizing more active NNMCs. This could be achieved through multiple pyrolysis steps, ball-milling steps, and control of the powder morphology by the addition of foaming agents and/or sulfur.